I don’t expect a state pension come retirement so I opened a SIPP many years ago. I’d recommend anyone with a child to open a private pension for them. 50p a day from an early age can make an enormous difference. The key is to start as early as possible. Your pot has not only tax relief but remains sheltered until you withdraw, 25% of the pot can be taken tax free which is a nice option to have as well.
Rules and further caps may apply as the rich took advantage of this - borrowing from their mortgage to live and slamming all earnings into a pension for the tax relief. Albeit at the risk of generating more gain than the cost of borrowing! This effectively allowed my mum to retire at 54. Opening a pension at the age of 18 seems overlooked.
There are plenty of pension calculators online. The results may shock you. Back in the day when I looked, Hargreaves & Lansdown were the ‘go-to’ company at the time. I’m still with them now. Transferring your private pot to other companies is easy FWIW.